Handle

We export a Handle component as a helper for your custom nodes:

import { Handle } from 'react-flow-renderer';

const targetHandleWithValidation = (
  <Handle
    type="target"
    position="left"
    isValidConnection={(connection) => connection.source === 'some-id'}
    onConnect={(params) => console.log('handle onConnect', params)}
    style={{ background: '#fff' }}
  />
);

Prop Types

Name	Type	Default	Description
type	'source' or 'target'	'source'	Defines the handle type
id	string	undefined	You only need this when you have multiple source or target handles (otherwise the node id is used)
position	'left', 'right', 'top' or 'bottom'	'top' for type target, 'bottom' for type source	Handle position
onConnect	function	undefined	Gets triggered on connect. This callback only gets executed on source handles.
isValidConnection	function	undefined	Receives a connection { target: 'some-id', source: 'another-id', sourceHandle: 'source handle id or null', targetHandle: 'target handle id or null' } as param, returns a boolean
isConnectable	boolean	true	boolean (this prop gets passed to your custom node component)
style	CSSProperties	undefined	Controls style attributes
className	string	undefined	Additional class name

Typescript: The interface of the Handle Prop Types are exported as HandleComponentProps.

Validation

The handle receives the additional class names connecting when the connection line is above the handle and valid if the connection is valid. You can find an example which uses these classes here.

Multiple Handles

If you need multiple source or target handles you can achieve this by creating a custom node. Normally you just use the id of a node for the source or target of an edge. If you have multiple source or target handles you need to pass an id to these handles. These ids can be used by an edge with the sourceHandle and targetHandle options, so that you can connect a specific handle. If you have a node with an id = 1 and a handle with an id = a you can connect this handle by using the node source=1 and the sourceHandle=a.

Dynamic Handles

If you are programmatically changing the position or number of handles in your custom node, you need to update the node internals with the useUpdateNodeInternals hook.

You can find an example of how to implement a custom node with multiple handles in the custom node guide or in the custom node example.